package com.jwetherell.datastructure.mathematics;

public class Division {
    
    public static final long division(int a, int b) {
        long result = ((long)a)/((long)b);
        return result;
    }
    
    public static final long divisionUsingLoop(int a, int b) {
        int absA = Math.abs(a);
        int absB = Math.abs(b);
        
        long temp = absA;
        long result = 0;
        while (temp>=0) {
            temp -= absB;
            if (temp>=0) result++;
        }
        return (a>0&&b>0 || a<0&&b<0)?result:-result;
    }
    
    public static final long divisionUsingRecursion(int a, int b) {
        int absA = Math.abs(a);
        int absB = Math.abs(b);
        
        long result = 1;
        int diff = absA-absB;
        if (diff > 0 && diff <= 1) {
            return result;
        } else if (diff < 0) {
            return 0;
        }

        result += divisionUsingRecursion(diff,absB);
        return (a>0&&b>0 || a<0&&b<0)?result:-result;
    }
    
    public static final long divisionUsingMultiplication(int a, int b) {
        int absA = Math.abs(a);
        int absB = Math.abs(b);
        
        int temp = absB;
        int counter = 0;
        while (temp <= absA) {
            temp = temp<<1;
            counter++;
        }
        absA -= absB<<(counter-1);
        long result = (long)Math.pow(2, counter-1);
        if (absB <= absA) result += divisionUsingMultiplication(absA,absB);
        return (a>0&&b>0 || a<0&&b<0)?result:-result;
    }

    public static final long divisionUsingShift(int a, int b) {
        int absA = Math.abs(a);
        int absB = Math.abs(b);
        int tempA, tempB, counter;

        long result = 0L;
        while (absA >= absB) {
            tempA = absA >> 1; //Right shift "a"
            tempB = absB;
            counter = 1;
            while (tempA >= tempB) { //Double "tempB" until it's larger than "tempA"
                tempB <<= 1;
                counter <<= 1; //Double the counter
            }
            absA -= tempB; //Subtract "tempB" from "a"
            result += counter; //Add counter (2^number of left shifts)
        }
        return (a>0&&b>0 || a<0&&b<0)?result:-result;
    }
    
    public static final long divisionUsingLogs(int a, int b) {
        long absA = Math.abs(a);
        long absB = Math.abs(b);
        double logBase10A = Math.log10(absA);
        double logBase10B = Math.log10(absB);
        double powOf10 = Math.pow(10, (logBase10A-logBase10B));
        long result = (long)Math.floor(powOf10);
        return (a>0&&b>0 || a<0&&b<0)?result:-result;
    }
}
